Introducer sheath and introducer assembly

ABSTRACT

An introducer sheath, which is formed from a tubular member provided with a hollow portion through which an elongated body is freely insertable, and which includes a distal portion and a main body portion, wherein the inner diameter of the distal portion is formed to become gradually smaller toward the distal side, and on the inner surface of the distal portion, there is provided a hydrophobic coating having a friction coefficient lower than the friction coefficient of the tubular member.

CROSS REFERENCES TO RELATED APPLICATIONS

This application contains subject matter disclosed in Japanese PatentApplication JP2011-133601 filed in the Japanese Patent Office on Jun.15, 2011 and International Application No. PCT/JP2012/059908 filed onApr. 11, 2012, the entire content of both of which is incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention generally relates to an introducer sheath and anintroducer assembly.

BACKGROUND DISCUSSION

In recent years, various forms of medical treatment and checkups havebeen performed using an elongated hollow and tubular medical instrumentreferred to as a catheter. Examples of such medical treatment methodsinclude administering medicine directly into a target lesion byutilizing the elongated property of the catheter, pushing, widening andopening a stenosis region inside a lumen in a living body (e.g., bloodvessel) using a catheter equipped with a balloon, which spreads bypressurization, at the distal end of the catheter, a shaving off andopening a target lesion using a catheter equipped with a cutter at thedistal portion of the catheter, applying a filler and closing ananeurysm, a bleeding place or a feeding vessel using a catheter. Also,there exists a medical treatment method in which in order to maintain astenosis region inside a lumen in a living body in an opened state, atube-shaped stent constituted to be in the shape of net for the sidesurface thereof is embedded and indwelled inside a lumen in a livingbody by using a catheter, or the like. Further, there exists a method ofsucking a liquid which has become excessive for the internal body, orthe like.

In case of carrying out a medical treatment and checkup or the likeusing a catheter, generally, an introducer sheath is introduced into asticking region formed in an arm or a leg by using a catheter introducerand a catheter or the like is percutaneously inserted into a diseasedregion such as a blood vessel or the like through a lumen of theintroducer sheath.

The introducer sheath is formed from a sheath tube which is a tubularmember provided with a hollow portion through which an elongated bodysuch as a catheter is freely insertable (see Japanese Unexamined PCTPatent Publication No. 2003-510134 and Japanese Unexamined PatentPublication No. 2002-291902). In Japanese Unexamined PCT PatentPublication No. 2003-510134, there is described a configuration ofproviding a hydrophilic coating on the inner surface of an introducersheath in order to reduce sliding resistance when inserting an elongatedbody such as a catheter through the introducer sheath. Also, JapaneseUnexamined Patent Publication No. 2002-291902 describes providing ahydrophilic coating on the outer surface of an introducer sheath inorder to secure the lubricity of the outer surface of the introducersheath. Japanese Unexamined Patent Publication No. 2002-291902 alsodescribes an introducer sheath in which the inner diameter at the distalportion thereof is formed to become gradually smaller toward the distalside (see FIG. 4 of Japanese Unexamined Patent Publication No.2002-291902).

When the inner diameter of the distal portion is formed gradually insmaller size toward the distal side as described in Japanese UnexaminedPatent Publication No. 2002-291902 sliding resistance between the innersurface of the distal portion and elongated body such as a catheterbecomes large and there occurs a phenomenon that slidability of thecatheter or the like is lowered. In order to improve such a situation,it is conceivable, as described in Japanese Unexamined PCT PatentPublication No. 2003-510134, that there is provided a hydrophiliccoating on the inner surface of the introducer sheath. However, the heatthat is produced at the time of carrying out a shape-application processof the distal portion using a die assembly acts excessively, and thereoccurs a phenomenon that the hydrophilic coating will peel, willdecompose, will degrade or the like. Consequently, the slidingresistance between the inner surface of the distal portion and theelongated body such as a catheter is not lowered substantially and so adifficulty arises in that it is not possible to achieve improvement inthe slidability of the catheter or the like.

Also, when pulling out the introducer sheath after being inserted insidethe blood vessel in a case in which there is provided a hydrophiliccoating on the outer surface of the sheath as described in JapaneseUnexamined Patent Publication No. 2002-291902, the hydrophilic coatingbecomes wet by the blood, lubricity occurs and a situation results inwhich the friction resistance is small. Consequently, it is possible topull out the introducer sheath rather smoothly. However, at thebeginning of the use of the introducer sheath, the hydrophilic coatingis under a dry condition, so that the sliding property is bad and thefriction resistance thereof is large. Consequently, when inserting itfrom the skin toward the inside of the blood vessel, the insertionresistance of the introducer sheath is undesirably large.

SUMMARY

An introducer sheath is disclosed in which the slidability of anelongated body such as a catheter or the like is achieved even in caseof the inner diameter of the distal portion being tapered so that theinner diameter becomes gradually smaller toward the distal end.

The disclosure here also describes an introducer sheath in which areduction in insertion resistance is achieved even under a dry conditionat the beginning of the use thereof. The introducer assembly is alsoconfigured to make it possible to insert the introducer sheath rathersmoothly by suppressing a turn-up of the distal portion.

According to one aspect of the disclosure here, an introducer sheath isformed from a tubular member provided with a hollow portion throughwhich an elongated body is freely insertable, and which includes adistal portion and a main body portion, and wherein the inner diameterof the distal portion is formed to become gradually smaller toward thedistal side, and on the inner surface of the distal portion, there isprovided a hydrophobic coating having a friction coefficient lower thanthe friction coefficient of the tubular member.

Another aspect of the disclosure involves an introducer sheath, which isformed from a tubular member provided with a hollow portion throughwhich an elongated body is freely insertable, and which includes adistal portion and a main body portion, wherein there is provided ahydrophilic lubricating coating on the outer surface of the main bodyportion, on the outer surface of the distal portion, there is provided ahydrophobic coating having a friction coefficient lower than thefriction coefficient of the hydrophilic lubricating coating during thedry period thereof.

Still another aspect of the disclosure involves an introducer assemblyformed by inserting a dilator as the elongated body through theintroducer sheath described above and by projecting a distal end of thedilator from the distal portion of the introducer sheath. Then, at leasta portion of the inner surface of the distal portion of the introducersheath and a portion of the outer surface of the dilator are attachedthrough the hydrophobic coating.

The inner diameter of the distal portion gradually becomes smallertoward the distal side, and the inner surface of the distal portion isprovided with a hydrophobic coating having a friction coefficient lowerthan the friction coefficient of the tubular member. Consequently, evenin case of forming the inner diameter of the distal portion graduallysmaller toward the distal side, it is possible to provide an introducersheath in which improvement in the slidability of an elongated body suchas a catheter or the like is achieved.

It is preferable for the outer surface of the distal portion to befurther provided with a hydrophobic coating. In this case, it ispossible to achieve reduction in insertion resistance even under a drycondition at the beginning of the use thereof.

A hydrophilic lubricating coating is preferably also provided on theouter surface of the main body portion, and a hydrophilic coating can beprovided on the outer surface of the distal portion, with thehydrophobic coating having a friction coefficient lower than thefriction coefficient of the hydrophilic lubricating coating during thedry period (i.e., before liquid is applied to the hydrophiliclubricating coating). Consequently, even under a dry condition at thebeginning of use, it is possible to provide an introducer sheath inwhich reduction in insertion resistance is achieved.

It is preferable for the hydrophobic coating to cover the upper portionof the hydrophilic lubricating coating at the boundary portion betweenthe distal portion and the main body portion. In this case, wheninserting the introducer sheath from the skin into the inside of theblood vessel, it never happens that the sheath gets stuck on the endsurface of the hydrophilic lubricating coating at the boundary portion.Consequently, it is possible to insert the introducer sheath smoothlyand it is possible to suppress peeling of the hydrophilic lubricatingcoating.

When absorbing the blood and swelling, it is preferable for thehydrophilic lubricating coating to exhibit a diameter approximatelyequal to or greater than the outer diameter of the hydrophobic coating.For example, when the hydrophilic lubricating coating swells byabsorbing blood, the hydrophilic lubricating coating has a diameterapproximately equal to or greater than the outer diameter of theoverlapping portion in which the hydrophobic coating overlaps thehydrophilic lubricating coating. In this case, when pulling out theintroducer sheath from the blood vessel, a step does not exist at theoverlapping portion in which the hydrophobic coating axially overlapsthe hydrophilic lubricating coating. Consequently, the resistance of thesurface of the introducer sheath with respect to the blood vessel andthe skin does not become surplus and it is possible to pull out theintroducer sheath relatively smoothly owing to both the coatings.

At least a portion of the inner surface of the distal portion of theintroducer sheath and a portion of the outer surface of the dilator areattached to each other through hydrophobic coating. Attaching the distalportion and the dilator to each other through hydrophobic coating helpssuppress turn-up of the distal portion when inserting the introducersheath and to insert the introducer sheath rather smoothly.

It is preferable for the hydrophobic coating to be formed from areactive-curing coating material and to be formed by reactively curingthe coating material in a state in which the dilator is passed throughthe introducer sheath. In this case, it is possible to carry out theformation of the hydrophobic coating and the attachment between theinner surface of the distal portion and the outer surface of the dilatorthrough this hydrophobic coating simultaneously, and it is possible toachieve simplification of the manufacturing process.

It is preferable the introducer assembly be configured so that the forceby which the introducer sheath and the dilator are attached to eachother is smaller than the force which acts on the attachment region whenthe dilator is pulled out from the introducer sheath. In this case, byemploying a configuration in which the attachment region is breakable inconjunction with the operation of pulling out the dilator, it ispossible to handle the introducer assembly while maintaining similarfeeling as heretofore and it never brings uncomfortable feeling to theuser.

It is preferable to attach the introducer sheath and the dilator byreactively curing the coating material depending on heat at the time ofgas sterilization. In this case, it is possible to carry out theformation of the hydrophobic coating and the attachment between theintroducer sheath and the dilator through this hydrophobic coating in apacked state simultaneously at the time of gas sterilization, and it ispossible to achieve simplification of the manufacturing process.

According to another aspect, an introducer sheath comprises: anelongated tubular member configured to be inserted in a living bodytissue and including a distal portion and a main body portion, with thedistal portion terminating distally at a distal-most end of the distalportion; and the distal-most end of the tubular member and thedistal-most end of the distal portion being the same; and the main bodyportion having a distal-most end connected to and extending proximallyfrom a proximal-most end of the distal portion so that the main bodyportion is located entirely proximally of the distal portion, the mainbody portion possessing an outer surface. The elongated tubular memberincludes a through hole extending throughout a longitudinal extent ofthe tubular member and opening to the distal-most end of the elongatedtubular member, with the through hole being configured to receive anelongated body. The elongated tubular member is comprised of a taperportion in which the inner diameter of the through hole gradually andcontinuously tapers to the distal-most end of the elongated tubularmember so that the inner diameter of the through hole in the taperportion is smaller at the distal-most end of the taper portion than at aproximal-most end of the taper portion. A hydrophilic lubricatingcoating is on the outer surface of the main body portion, and ahydrophobic coating is on the inner surface of the through hole in thetaper portion, the hydrophobic coating extending proximally from thedistal-most end of the tubular member toward the main body portion. Thehydrophobic coating possesses a friction coefficient lower than thefriction coefficient of the hydrophilic lubricating coating before thehydrophilic lubricating coating contacts liquid.

BRIEF DESCRIPTION OF THE DRAWINGS

Other aspects and characteristics of the introducer sheath and theintroducer assembly disclosed here will become more apparent from thefollowing detailed description of embodiments disclosed as examples,considered with reference to the accompanying drawing figures whichillustrate the embodiments disclosed as examples.

FIG. 1 is a plan view of an introducer assembly disclosed here by way ofexample packaged inside a packaging film.

FIG. 2 is an exploded plan view of an introducer sheath and a dilator ofan introducer assembly.

FIG. 3 is a longitudinal cross-sectional view of the introducer sheathdisclosed here according to one embodiment disclosed by way of example.

FIG. 4A is an enlarged cross-sectional view of a portion of theintroducer sheath which is circled in FIG. 3.

FIG. 4B is a cross-sectional view similar to FIG. 4A showing a stateafter an introducer sheath is inserted inside a lumen in a living body(e.g., a blood vessel).

FIG. 5 is a longitudinal cross-sectional view of an introducer sheathaccording to a second embodiment.

FIG. 6 is a longitudinal cross-sectional view of an introducer sheathaccording to a third embodiment.

FIG. 7 is a longitudinal cross-sectional view of an introducer sheathaccording to a fourth embodiment.

FIG. 8 is a longitudinal cross-sectional view of an introducer sheathaccording to a further embodiment.

DETAILED DESCRIPTION

Set forth below with reference to the attached drawings is a detaileddescription of examples of the introducer sheath and introducer assemblydisclosed here. The drawings identify common features by commonreference numerals, and so a detailed discussion of such features andaspects of the sheath and assembly which are the same as previouslydescribed will not be repeated. Also, the size ratio of features shownin the drawings is exaggerated for convenience of explanation and it isdifferent from the actual ratio.

An introducer assembly 10 is a device for securing or providing anaccess route to the inside of a lumen in a living body (e.g., a bloodvessel). In the following explanation, the hand-side operation unit sideor end of the device is referred to as the “proximal side” or “proximalend”, and the side or end to be inserted into the inside of the lumen ina living body is referred to as the “distal side” or “distal end”.

FIG. 1 illustrates the introducer assembly 10 packaged inside apackaging film 40, and FIG. 2 illustrates, in an exploded manner, asheath 20 for introducer and a dilator 30 of the introducer assembly 10.

Generally speaking, and with reference to FIG. 1 and FIG. 2, theintroducer assembly 10 includes the introducer sheath 20 and the dilator30. In this embodiment disclosed as one example of the introducerassembly, the introducer sheath 20 and the dilator 30 are integratedbeforehand and packaged inside the packaging film 40. That is, theintegrated introducer sheath 20 and dilator 30 are entirely covered byand enclosed within the packaging film in a sterile state. Theintroducer sheath 20 is provided with a sheath tube 21, a sheath hub 22attached to the proximal end of the sheath tube 21, and a hemostasisvalve 23 attached to the proximal end of the sheath hub 22. The dilator30 is provided with a dilator tube 31 and a dilator hub 32 attached tothe proximal end of the dilator tube 31. The introducer assembly 10 willnow be described in more detail.

The introducer sheath 20 is indwelled inside the lumen in a living bodyand is a sheath for being introduced into the inside of the lumen in aliving body, with an elongated body such as a catheter, a guide wire, anembolus object or the like being inserted therethrough in the insidethereof.

The sheath tube 21 is introduced percutaneously into the inside of thelumen in a living body (e.g., blood vessel).

As the constituent material of the sheath tube 21, it is possible touse, for example, a polymer material such as a polyolefin (e.g.polyethylene, polypropylene, polybutene, ethylene-propylene copolymer,ethylene-vinyl acetate copolymer, ionomer, a mixture of two kinds ormore of these, or the like), polyolefin elastomer, a cross-linked bodyof polyolefin, polyvinyl chloride, polyamide, polyamide elastomer,polyester, polyester elastomer, polyurethane, polyurethane elastomer,fluororesin, polycarbonate, polystyrene, polyacetal, polyimide,polyetherimide or the like, a mixture of these, or the like. It ispossible to use ethylenetetrafluoroethylene copolymer (ETFE) favorably.

A side port 24 which communicates with the inside of the sheath tube 21is formed at the sheath hub 22. One end of a tube 25 having flexibility,which is made, for example, of polyvinyl chloride, is connected to theside port 24 in a liquid-tight manner. On the other end of the tube 25,for example, a T-shape stopcock 26 is mounted. A liquid such asphysiological saline is injected into the introducer sheath 20 from aport of this T-shape stopcock 26 through the tube 25.

For the constituent material of the sheath hub 22, there is nolimitation in particular, but a hard material such as a hard resin ispreferably used. As specific examples of the hard resin, it is possibleto cite, for example, polyolefins such as polyethylene, polypropyleneand the like, polyamides, polycarbonates, polystyrenes, and the like.

The hemostasis valve 23 is constituted by an elastic member possessingapproximately an elliptical membrane shape (disc shape) and is fixed ina liquid-tight manner with respect to the sheath hub 22.

The constituent material forming the hemostasis valve 23 is notparticularly limited. Examples of suitable materials include siliconerubber, latex rubber, butyl rubber, isoprene rubber or the like, whichis an elastic member.

The dilator 30 is used, when inserting the introducer sheath 20 into theblood vessel, to prevent breakage of the sheath tube 21, to expand thediameter of a trephination in the skin, and so on.

The dilator tube 31 is inserted inside the sheath tube 21. As shown inFIG. 1, this creates a state in which the distal end 33 of the dilatortube 31 projects distally beyond the distal end of the sheath tube 21.

The constituent material forming the dilator tube 31 is not particularlylimited. Examples of materials include a polymer material such aspolyolefin (e.g. polyethylene, polypropylene, polybutene,ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer,a mixture of two kinds or more of these, or the like), polyolefinelastomer, a cross-linked body of polyolefin, polyvinyl chloride,polyamide, polyamide elastomer, polyester, polyester elastomer,polyurethane, polyurethane elastomer, fluororesin, polycarbonate,polystyrene, polyacetal, polyimide, polyetherimide or the like, amixture of these, or the like.

The dilator hub 32 is held detachably with respect to the sheath hub 22.The constituent material forming the dilator hub 32 is also not limited,but a hard material such as a hard resin is favorably used. As specificexamples of the hard resin, it is possible to cite, for example,polyolefins such as polyethylene, polypropylene and the like,polyamides, polycarbonates, polystyrenes, and the like.

FIGS. 3 and 4A illustrate features and aspects of an introducer sheath20 according to one example of a first embodiment.

Referring generally to FIG. 3, the introducer sheath 20 is formed by thesheath tube 21 (constituting an example of a tubular member) providedwith a hollow portion or through hole 21 a through which an elongatedbody such as a catheter is freely insertable, and the sheath is providedwith a sheath distal portion 50 and a sheath main body portion 60. Thesheath tube 21 possesses a distal end portion terminating at thedistal-most end of the sheath tube 21, and the sheath main body portion60 has a distal-most end connected to the proximal-most end of thesheath distal portion 50. The sheath distal portion 50 includes a taperportion 51, whose outer diameter tapers in the distal direction from alarger outer diameter to a smaller outer diameter, and a straightportion non-taper portion 52 which extends approximately in parallelwith the axis line and which is not tapered.

As for the introducer sheath 20, the inner diameter φ_(a) of the sheathdistal portion 50 is configured to become gradually smaller toward thedistal end of the sheath distal portion 50. The inner diameter of thestraight non-taper portion 52 is constant and does not taper. Theintroducer sheath 20 is further provided, on the inner surface 50 a ofthe sheath distal portion 50, with a hydrophobic coating 71 having afriction coefficient lower than the friction coefficient of the sheathtube 21. In the illustrated example, the hydrophobic coating 71 extendsover or covers the entire length of the inner surface 50 a of the sheathdistal portion 50 and the entire length of the inner surface 60 a of thesheath main body portion 60.

The outer surface 50 b of the sheath distal portion 50 is furtherprovided with a hydrophobic coating 72. The hydrophobic coating 72 willbe described in more detail later.

The introducer sheath 20 is provided with a hydrophilic lubricatingcoating 73 on the outer surface 60 b of the sheath main body portion 60.The introducer sheath 20 is further provided, on the outer surface 50 bof the sheath distal portion 50, with the hydrophobic coating 72 havinga friction coefficient lower than the friction coefficient of thehydrophilic lubricating coating 73 during the dry period.

Here, the term “dry” such as used in the phrase “during the dry period”broadly means a state in which the hydrophilic lubricating coating 73 isnot wet and cannot exert sufficient lubricity. Therefore, it is notnecessary to specify the degree of “dry” according to the temperatureand the humidity.

Regarding the size of the introducer sheath 20, in a case in which thesize of the catheter is 6Fr, the length of the sheath distal portion 50is 3 mm to 4 mm, the inner diameter φ_(a) of the most distal end is 1.98mm to 2.13 mm and the inner diameter φ_(b) of the sheath main bodyportion 60 is 2.22 mm. The size of the introducer sheath 20 is notlimited to the abovementioned dimensions.

The hydrophobic coatings 71, 72 are formed by coating the noted surfaceswith a hydrophobic material. Examples of the hydrophobic materialinclude reactive-curing silicone, polytetrafluoroethylene (PTFE),fluorinatedethylenepropylene (FEP) or the like.

The hydrophilic lubricating coating 73 is formed by coating the notedsurface with a hydrophilic material. Examples of the hydrophilicmaterial include an acrylamide-based polymer material (e.g.,polyacrylamide, a block copolymer ofpolyglycidylmethacrylate-dimethylacrylamide (PGMA-DMAA)), acellulose-based polymer material, a polyethylene oxide-based polymermaterial, a maleic anhydride-based polymer material (e.g., a maleicanhydride copolymer such as methylvinylether-maleic anhydridecopolymer), water-soluble nylon, polyvinyl alcohol, polyvinylpyrrolidoneor the like.

It is necessary for the hydrophobic coating 72 on the outer surface 50 bat the sheath distal portion 50 to at least cover the taper portion 51of the sheath distal portion 50. The taper portion 51 of the sheathdistal portion 50 is a region to which the greatest resistance isapplied at the time of insertion. Consequently, when the taper portion51 which is not provided with the hydrophobic coating 72 is exposed tothe outer surface 50 b, there occurs a phenomenon that reduction ininsertion resistance is hampered and this is the reason for the coating72. It is desirable for the region provided with the hydrophobic coating72 within the straight portion 52 of the sheath distal portion 50 tohave a range of less than ½ of the effective length of the introducersheath 20. This is derived in consideration of a balance between theresistance reduction effect at the time when the introducer sheath 20 isinserted and the resistance reduction effect at the time when it ispulled out.

In a case in which the hydrophobic coatings 71, 72 of the inner surface50 a and the outer surface 50 b of the sheath distal portion 50 areformed by reactive-curing silicone, the hydrophobic coatings 71, 72themselves cure and the sheath distal portion 50 cures, thereby makingit possible to suppress turn-up of the sheath distal portion 50.

The introducer sheath 20 can be manufactured as follows.

First, the hydrophilic lubricating coating 73 is formed only on theouter surface 60 b of the sheath main body portion 60 of the introducersheath 20. To achieve this, a cored bar is inserted through the sheathtube 21. With the cored bar inside the sheath tube 21, a coating ofhydrophilic material is applied to the sheath main body portion 60 ofthe sheath tube 21 to thereby form the hydrophilic lubricating coating73. This coating can be applied by, for example, dipping the sheath mainbody portion 60 of the sheath tube 21 in hydrophilic material. Examplesof the hydrophilic material which can be used includepolyglycidylmethacrylate-dimethylacrylamide (PGMA-DMAA). Examples of thematerial which can be used to form the sheath tube 21 includeethylenetetrafluoroethylene copolymer (ETFE).

Subsequently, a process of shape-application on the sheath distalportion 50 is carried out. For this process, there is used a dieassembly in which there is formed a recess having an inner-surface shapewhich conforms to the taper shape of the sheath distal portion 50. Thedie assembly is heated by a high frequency power supply. The distal endof the sheath tube 21 is pressed into the recess of the die assembly.Then, the inner-surface shape of the recess is transferred to the distalend of the sheath tube 21 and at the sheath distal portion 50, there isformed the taper portion 51 at which the outer surface 50 b tapers.

Subsequently, the hydrophobic coating 71 is formed over the whole lengthof the inner surface 50 a of the sheath distal portion 50 and the wholelength of the inner surface 60 a of the sheath main body portion 60. Theinner surfaces 50 a, 60 a of the introducer sheath 20 are thus coatedwith a hydrophobic material and the hydrophobic coating 71 is formed.Further, the hydrophobic coating 72 is also formed on the outer surface50 b of the sheath distal portion 50. The sheath distal portion 50 isdipped into a hydrophobic material and the hydrophobic coating 72 isformed. An example of the hydrophobic material which can be usedincludes reactive-curing silicone is used. As this hydrophobic material,a material is used which has a friction coefficient lower than thefriction coefficient of the hydrophilic lubricating coating 73 duringthe dry period thereof. In the above-mentioned example, reactive-curingsilicone having a friction coefficient lower than the frictioncoefficient of ETFE during the dry period thereof is used as thehydrophobic material.

By way of the processes mentioned above, the introducer sheath 20 shownin FIG. 3 is formed.

For the introducer sheath 20 of this disclosed example of the firstembodiment, the inner diameter φ_(a) of the most distal end of thesheath 20 is smaller than the outer diameter of the elongated body suchas a catheter which is to be inserted into the sheath 20, but on theinner surface 50 a of the sheath distal portion 50, there is providedthe hydrophobic coating 71 (coating composed of reactive-curingsilicone) having a friction coefficient lower than the frictioncoefficient of the raw material (e.g., ETFE) of the sheath tube 21.Consequently, the sliding resistance between the inner surface 50 a ofthe sheath distal portion 50 and the elongated body such as a catheteris lowered, and it is possible to achieve improvement in the slidabilityof the catheter or the like.

If the inner surface 50 a of the sheath distal portion 50 was providedwith a hydrophilic lubricating coating, a process for activating the rawmaterial of the sheath tube 21 would be necessary, and it would benecessary to form the hydrophilic lubricating coating before carryingout the shape-application process on the sheath distal portion 50. Theheat created at the time of carrying out the shape-application processon the sheath distal portion 50 using the die assembly acts excessivelyand there occurs a phenomenon that the hydrophilic coating peels,decomposes, degrades or the like. Consequently, the sliding resistancebetween the inner surface 50 a of the sheath distal portion 50 and theelongated body such as a catheter would not be lowered substantially,and so it would not be possible to achieve improvement in theslidability of the elongated body such as the catheter or the like.

On the other hand, in the case of the hydrophobic coating 71 on theinner surface 50 a of the sheath distal portion 50, the coating 71 canbe formed by coating with a hydrophobic material after carrying out theshape-application process on the sheath distal portion 50. Peeling,decomposition, degradation and the like of the hydrophobic coating 71thus do not occur. Therefore, as mentioned above, the sliding resistancebetween the inner surface 50 a of the sheath distal portion 50 and theelongated body such as a catheter is lowered and it is possible toachieve improvement in the slidability of the elongated body such as thecatheter or the like.

The introducer sheath 20 is further provided with the hydrophobiccoating 72 having a friction coefficient lower than the frictioncoefficient of the hydrophilic lubricating coating 73 during the dryperiod of the coating 73, on the outer surface 50 b of the sheath distalportion 50 to which the greatest resistance is applied at the time ofinsertion. The hydrophilic coating has a poor sliding property under adry condition, but by providing the hydrophobic coating 72 on the outersurface 50 b of the sheath distal portion 50, it is possible to lowerthe insertion resistance of the introducer sheath 20 when inserting thesheath from the skin into the blood vessel. When pulling out theintroducer sheath 20 after its insertion into the blood vessel, thehydrophilic lubricating coating 73 becomes wet by the blood and exhibitslubricity, so that it is possible to pull it out relatively smoothly.Preferably, the hydrophilic lubricating coating 73 and the hydrophobiccoating 72 are configured so that when the hydrophilic lubricatingcoating swells by absorbing blood, the hydrophilic lubricating coatinghas an outer diameter approximately equal to or greater than the outerdiameter of the hydrophobic coating.

In this manner, according to the introducer sheath 20 of the firstembodiment disclosed by way of example, even in a case in which theinner diameter φa of the sheath distal portion 50 is configured tobecome gradually smaller toward the distal end, it is possible toachieve improvement in the slidability of the elongated body such as acatheter. Furthermore, according to the introducer sheath 20 of thisembodiment, it is possible to achieve reduction in the insertionresistance even under a dry condition at the beginning of the usethereof.

FIG. 4A shows a structure in which the hydrophobic coating 72 on theouter surface 50 b of the sheath distal portion 50 and the hydrophiliclubricating coating 73 on the outer surface 60 b of the sheath main bodyportion 60 axially overlap each other.

As shown in FIG. 4A, at the boundary portion between the sheath distalportion 50 and the sheath main body portion 60, it is desirable toemploy a structure in which the hydrophobic coating 72 overlies thehydrophilic lubricating coating 73. This is because at the time ofinsertion of the introducer sheath 20 from the skin (through the skin)into the blood vessel, the sheath does not get stuck on the end surfaceof the hydrophilic lubricating coating 73 at the boundary portion. Byemploying such a construction, it is possible to relatively smoothlyinsert the introducer sheath 20 and it is even possible to suppresspeeling of the hydrophilic lubricating coating 73.

FIG. 4B shows the state of the hydrophilic lubricating coating 73 andthe hydrophobic coating 72 after insertion of the introducer sheath 20into the blood vessel.

As shown in FIG. 4B, the hydrophilic lubricating coating 73 absorbsblood and swells, and the diameter of the hydrophilic lubricatingcoating 73 becomes approximately equal to or larger than the outerdiameter of the hydrophobic coating 72. By virtue of this, when theintroducer sheath 20 is pulled out from the blood vessel, theoverlapping portion at which the proximal portion of the hydrophobiccoating 72 axially overlaps the distal portion of the hydrophiliclubricating coating 73 does not exhibit a significant level difference.That is, the larger outer diameter of the proximal portion of thehydrophobic coating 72 relative to the outer diameter of the distalportion of the hydrophilic lubricating coating 73 that exists beforeinsertion of the introducer sheath 20 into the blood vessel as shown inFIG. 4A is preferably eliminated, so that after insertion of theintroducer sheath 20 into a blood vessel as shown in FIG. 4B, the outerdiameter of the distal portion of the hydrophilic lubricating coating 73is equal to or larger than the outer diameter of the proximal portion ofthe hydrophobic coating 72. Therefore, the resistance of the surface ofthe introducer sheath 20 with respect to the blood vessel and thepuncture site of the skin does not become excessive and it is possibleto pull out the introducer sheath 20 relatively smoothly due to both thecoatings 72 and 73.

According to experimentation, by providing the hydrophobic coating 71formed from reactive-curing silicone, the sliding resistance of theinner surface 50 a at the sheath distal portion 50 is lowered by as muchas approximately 80% compared with a case in which the hydrophobiccoating 71 was not applied. Further, by providing the hydrophobiccoating 72 formed from reactive-curing silicone, the penetrationresistance of the outer surface 50 b at the sheath distal portion 50 islowered by as much as approximately 30% compared with a case in which ahydrophilic lubricating coating was applied. In this manner, it wasconfirmed by experimentation that high effectiveness can be obtainedboth in relation to reduction in the sliding resistance of the innersurface 50 a at the sheath distal portion 50 and in relation toreduction in the penetration resistance of the outer surface 50 b at thesheath distal portion 50.

FIG. 5 illustrates an introducer sheath according to a second embodimentwhich represents a modified example of the first embodiment.

This second embodiment is an example in which the manufacturingprocedure of an introducer sheath 120 is modified with respect to thefirst embodiment described above.

In the manufacturing procedure associated with manufacturing theembodiment shown in FIG. 5, first, the hydrophilic lubricating coating73 is formed not only on the outer surface 60 b of the sheath main bodyportion 60 of the introducer sheath 120 but also on the outer surface 50b of the sheath distal portion 50. A cored bar is inserted through thesheath tube 21, and by dipping the sheath tube with cored bar into ahydrophilic material, the hydrophilic lubricating coating 73 is formedon the whole or entirety of the outer surfaces 50 b, 60 b of theintroducer sheath 120.

Subsequently, a shape-application process on the sheath distal portion50 is carried out. Depending on the heat which acts or is created whenthe shape-application process on the sheath distal portion 50 is carriedout using a die assembly, the hydrophilic lubricating coating 73 on theouter surface 50 b of the sheath distal portion 50 disappears, thelubricity thereof is deactivated although the coating itself remains,and the like. This second embodiment shows the latter state in which thelubricity is deactivated, though the coating itself remains. As shown inFIG. 5, the coating 73 a whose lubricity has been deactivated remains onthe outer circumference surface 50 b of the sheath distal portion 50.

Subsequently, the hydrophobic coating 71 is formed over the entirelength of the inner surface 50 a of the sheath distal portion 50 andover the entire length of the inner surface 60 a of the sheath main bodyportion 60. The inner surfaces 50 a, 60 a of the introducer sheath 20are thus coated with a hydrophobic material and the hydrophobic coating71 is formed. Further, the hydrophobic coating 72 is formed also on theouter surface of the coating 73 a, whose lubricity has been deactivated,at the sheath distal portion 50. By dipping the sheath distal portion 50into a hydrophobic material, the hydrophobic coating 72 is formed.

By way of the processes mentioned above, the introducer sheath 120 shownin FIG. 5 is formed. In this embodiment of the introducer sheathdisclosed by way of example, the hydrophobic coating 72 is formed on thecoating 73 a whose lubricity has been deactivated, so that functionalgroups remaining in the coating 73 a are coupled with the hydrophobiccoating. Consequently, it is possible to improve the fixation propertycompared with a case in which a sheath made ofethylene-tetra-fluoro-ethylene copolymer (ETFE) is directly covered witha hydrophobic coating.

FIG. 6 illustrates an introducer sheath 220 according to a thirdembodiment.

With reference to FIG. 6, the introducer sheath 220 of this embodimentincludes a hydrophilic lubricating coating 74 on the inner surface 60 aof the sheath main body portion 60 and in terms of this aspect, it isdifferent from the introducer sheath 20 of the first embodiment which isprovided with the hydrophobic coating 71 on the inner surface 60 a ofthe sheath main body portion 60.

The introducer sheath 220 of this embodiment, similar to the firstembodiment described above by way of example, possesses an innerdiameter φ_(a) of the sheath distal portion 50 that becomes graduallysmaller toward the distal side. The inner surface 50 a of the sheathdistal portion 50 is provided with a hydrophobic coating 75 having afriction coefficient lower than the friction coefficient of the sheathtube 21. Also, for the introducer sheath 220, similar to the firstembodiment, the hydrophilic lubricating coating 73 is provided on theouter surface 60 b of the sheath main body portion 60, and thehydrophobic coating 72 having a friction coefficient lower than thefriction coefficient of the hydrophilic lubricating coating 73 duringthe dry period thereof is provided on the outer surface 50 b of thesheath distal portion 50.

The size, the hydrophobic material and the hydrophilic material of theintroducer sheath 220 are similar to those of the first embodimentdescribed above.

The introducer sheath 220 is manufactured as follows.

First, the inner surfaces 50 a, 60 a and the outer surfaces 50 b, 60 bof the introducer sheath 220 are subjected to plasma treatment so that aprocess for activating the raw-material surface layer of the sheath tube21 is carried out.

Subsequently, the hydrophilic lubricating coatings 73, 74 are formed onthe inner surfaces 50 a, 60 a and the outer surfaces 50 b, 60 b of theintroducer sheath 220. By dipping the inner surfaces 50 a, 60 a and theouter surfaces 50 b, 60 b of the sheath tube 21 into a hydrophilicmaterial, the hydrophilic lubricating coating 73 is formed. Thehydrophilic material used is, for example,polyglycidylmethacrylate-dimethylacrylamide (PGMA-DMAA) or the like. Thematerial of the sheath tube 21 is, for example,ethylenetetrafluoroethylene copolymer (ETFE) or the like.

Subsequently, a shape-application process on the sheath distal portion50 is carried out. In this process, a die assembly is used in whichthere is formed a recess having an inner-surface shape which conforms tothe tapered outer shape of the sheath distal portion 50. The dieassembly is heated by a high frequency power supply. The distal end ofthe sheath tube 21 is pressed into the recess of the die assembly. Then,the inner-surface shape of the recess is transferred to the distal endof the sheath tube 21, and the sheath distal portion 50 is formed withthe taper portion 51 at which the outer surface 50 b tapers. In theformer process, at the time of dipping into the hydrophilic material,the hydrophilic lubricating coating is formed on the inner surface 50 aand the outer surface 50 b of the sheath distal portion 50. However,depending on the heat which acts at the time of carrying out theshape-application process on the sheath distal portion 50 by using thedie assembly, the hydrophilic lubricating coating on the inner surface50 a and the outer surface 50 b of the sheath distal portion 50disappears, the lubricity thereof is deactivated, though the coatingitself remains, and so on. This second modified embodiment shows theformer state in which the hydrophilic lubricating coating hasdisappeared due to the shape-application process.

Subsequently, the hydrophobic coatings 75, 72 are formed on the innersurface 50 a and the outer surface 50 b of the sheath distal portion 50.The hydrophobic coatings 75, 72 are formed at the portions at which thehydrophilic lubricating coating has disappeared. By dipping the sheathdistal portion 50 into a hydrophobic material, the hydrophobic coatings75, 72 are formed. Examples of the hydrophobic material used includereactive-curing silicone or the like. For this hydrophobic material, amaterial is used which has a friction coefficient lower than thefriction coefficient of the hydrophilic lubricating coating 73 duringthe dry period thereof. In the above-mentioned example, reactive-curingsilicone having a friction coefficient lower than the frictioncoefficient of ETFE during the dry period thereof is used as thehydrophobic material.

By way of the processes mentioned above, the introducer sheath 220 shownin FIG. 6 is formed.

For the introducer sheath 220 of this third embodiment, similar to theembodiments described above, the inner diameter φa of the most distalend of the sheath is smaller than the outer diameter of the elongatedbody such as a catheter, but on the inner surface 50 a of the sheathdistal portion 50, there is provided the hydrophobic coating 75 (coatingcomposed of reactive-curing silicone) having a friction coefficientlower than the friction coefficient of the raw material (e.g., ETFE) ofthe sheath tube 21. Consequently, the sliding resistance between theinner surface 50 a of the sheath distal portion 50 and the elongatedbody such as a catheter is lowered, which makes it possible to achieveimprovement in the slidability of the catheter or the like.

Also, in case of forming the hydrophobic coatings 75, 72 on the innersurface 50 a and the outer surface 50 b of the sheath distal portion 50,it is possible to form them by dipping into a hydrophobic material aftercarrying out the shape-application process on the sheath distal portion50, and peeling, decomposition, degradation and the like of thehydrophobic coatings 75, 72 do not occur. Therefore, as mentioned above,the sliding resistance between the inner surface 50 a of the sheathdistal portion 50 and the elongated body such as a catheter is lowered,in which it is possible to achieve improvement in the slidability of thecatheter or the like. The introducer sheath 220 is further provided withthe hydrophobic coating 72 having a friction coefficient lower than thefriction coefficient of the hydrophilic lubricating coating 73 duringthe dry period thereof, on the outer surface 50 b of the sheath distalportion 50. The hydrophilic coating has a poor sliding property under adry condition, but by providing the hydrophobic coating 72 on the outersurface 50 b of the sheath distal portion 50, it is possible to lowerthe insertion resistance of the introducer sheath 220 when inserting itfrom (through) the skin into the blood vessel. When the introducersheath 220 is pulled out after its insertion it into the blood vessel,the hydrophilic coating becomes wet by the blood and exhibits lubricity,so that it is possible to pull it out rather smoothly.

In this manner, according to the introducer sheath 220 of the thirdembodiment disclosed by way of example, even in a case in which theinner diameter φ_(a) of the sheath distal portion 50 gradually becomessmaller toward the distal end, it is possible to achieve improvement inthe slidability of the elongated body such as a catheter andfurthermore, it is possible to achieve reduction in insertion resistanceeven under a dry condition at the beginning of use.

Similar to the first embodiment described above, it is desirable for theboundary portion between the sheath distal portion 50 and the sheathmain body portion 60 to employ a structure in which the hydrophobiccoating 72 lies over the hydrophilic lubricating coating 73 as shown inFIG. 4A. This is because it is possible to insert the introducer sheath220 relatively smoothly and it is also possible to suppress peeling ofthe hydrophilic lubricating coating 73.

FIG. 7 illustrates the introducer sheath 20 and the dilator 30 in anintroducer assembly 10 according to another embodiment.

The introducer assembly 10 is constituted such that the dilator 30 as anelongated body is inserted through the introducer sheath 20 of the firstembodiment and the distal end of the dilator tube 31 of the dilator 30projects from (i.e., distally beyond) the sheath distal portion 50. Inthis introducer assembly 10, at least a portion of the inner surface 50a of the sheath distal portion 50 and a portion of the outer surface 30b of the dilator 30 are attached to each other through the hydrophobiccoating 71. In the drawing, the sheath distal portion 50 and the dilator30 are attached to each other at the portion indicated by a referencenumeral A.

By attaching the sheath distal portion 50 and the dilator 30 to eachother, a turn-up of the sheath distal portion 50 is suppressed when theintroducer sheath 20 is inserted from (through) the skin into the bloodvessel, whereby it is possible to insert the introducer sheath 20 rathersmoothly.

There is no specific limitation on the region (axial extent of theregion) at which the inner surface 50 a of the sheath distal portion 50and the outer surface 30 b of the dilator 30 are attached to each other,but from a view point of suppressing turn-up of the sheath distalportion 50, it is preferable to perform the attachment at the positionwhich nears the distal end side as much as possible.

It is possible for the hydrophobic coating 71 to be formed by areactive-curing coating material, for example reactive-curing silicone.In this case, it is desirable for the hydrophobic coating 71 to beformed by reactively curing the coating material in a state in which thedilator 30 is inserted through the introducer sheath 20. This isbecause, according to such an introducer assembly 10, it is possible tosimultaneously carry out formation of the hydrophobic coating 71 andattachment between the inner surface 50 a of the sheath distal portion50 and the outer surface 30 b of the dilator 30 through this hydrophobiccoating 71 and it is possible to achieve simplification of themanufacturing process.

Further, by forming the hydrophobic coatings 71, 72 on the inner surface50 a and the outer surface 50 b of the sheath distal portion 50 from thecuring reactive silicone, the hydrophobic coatings 71, 72 themselvescure, and the sheath distal portion 50 cures, which makes it possible tosuppress turn-up of the sheath distal portion 50 even further.

In the introducer assembly 10, it is desirable for the force, by whichthe introducer sheath 20 and the dilator 30 are attached to each other,to be smaller than the force which acts on the attachment region whenthe dilator 30 is pulled out from the introducer sheath 20.

This is because, by configuring the attachment region to be a breakableattachment region at which the attachment between the inner surface 50 aof the sheath distal portion 50 and the outer surface 30 b of thedilator 30 is breakable, it is possible to use or operate the introducerassembly 10 while maintaining similar feelings felt until without theattachment, which does not give uncomfortable feelings to the operator.

The introducer assembly 10 makes it possible to attach the introducersheath 20 and the dilator 30 to each other by reactively curing acoating material depending on the heat at the time of gas sterilization.

This is because, according to such an introducer assembly 10, it ispossible to simultaneously carry out formation of the hydrophobiccoating 71 and attachment of the introducer sheath 20 and the dilator 30to each other through this hydrophobic coating 71 in a packed state atthe time of EOG sterilization, whereby it is possible to achievesimplification of the manufacturing process.

FIG. 8 is a cross-sectional view showing an introducer sheath 320according to a further embodiment.

With respect to the introducer sheaths 20, 120, 220 mentioned above, theinner diameter φ_(a) of the sheath distal portion 50 is formed to becomegradually smaller toward the distal side and on the inner surface 50 aof the sheath distal portion 50, and there is formed the hydrophobiccoating 71 having a friction coefficient lower than the frictioncoefficient of the sheath tube 21. It is possible to lower the slidingresistance of the inner surface 50 a by providing the hydrophobiccoating 71, so that it becomes possible to achieve reduction in slidingresistance even if the contact area with respect to the catheter or thelike increases.

The introducer sheath 320 of this embodiment shown in FIG. 8 employs aconfiguration in which the inner diameter of the sheath distal portion50 is formed with uniform size without diameter reduction. In terms ofthis aspect, this fourth modified version of the introducer sheathdiffers from the first to third embodiments.

In more detail, as shown in FIG. 8, the introducer sheath 320 accordingto this embodiment is formed by a sheath tube 321 (corresponding totubular member) provided with a hollow portion 321 a through which theelongated body such as a catheter is freely insertable. The introducersheath 320 is provided with the sheath distal portion 50 (correspondingto distal portion) and the sheath main body 60 (corresponding to mainbody portion). The sheath distal portion 50 includes a taper portion 51which tapers and a straight portion 52 which extends approximately inparallel with the axial line.

As for the introducer sheath 320, the inner diameter of the sheathdistal portion 50 is not reduced and is formed uniformly as the innerdiameter φ_(a). Also the inner diameter of the sheath main body 60 isformed uniformly as the inner diameter φ_(a). The introducer sheath 320is further provided, on the inner surface 50 a of the sheath distalportion 50, with the hydrophobic coating 71 having a frictioncoefficient lower than the friction coefficient of the sheath tube 321.In this fourth exemplified embodiment, there is provided the hydrophobiccoating 71 over the whole lengths of the inner surface 50 a of thesheath distal portion 50 and the inner surface 60 a of the sheath mainbody 60.

With respect to an aspect in which there is provided, on the outersurface 60 b sheath main body 60, the hydrophilic lubricating coating73; an aspect in which there is provided, on the outer surface 50 b ofthe sheath distal portion 50, the hydrophobic coating 72 having afriction coefficient lower than the friction coefficient of thehydrophilic lubricating coating 73 during the dry period thereof; anaspect of the constituent materials of the sheath tube 321; an aspect ofthe constituent materials of the hydrophobic coatings 71, 72; and anaspect of the constituent materials of the lubricating coating 73, theyare similar to those explained in the first exemplified embodiment. Asfor the manufacturing procedure of the introducer sheath 320, it issimilar to that explained in the first exemplified embodiment except anaspect in which a straight-shape cored bar is inserted through thesheath tube 321 such that the inner diameter of the sheath tube 321 isnot reduced when carrying out the shape-application process on thesheath distal portion 50.

According to the introducer sheath 320 of this embodiment, it ispossible to achieve improvement in the slidability of the elongated bodysuch as a catheter even in case of forming the inner diameter of thesheath tube 321 uniformly. Furthermore, according to the introducersheath 320, it is possible to achieve reduction in insertion resistanceeven under a dry condition at the beginning of the use thereof.

The introducer sheaths 20, 120, 220, 320 and the introducer assembly 10disclosed here were explained based on various embodiments disclosed andillustrated in the drawing figures by way of example. But it is possibleto employ features and aspects varying from those described andillustrated.

For example, in a case in which reduction in the sliding resistance ofthe inner surface 50 a in the sheath distal portion 50 is to be mainlyachieved, it is sufficient if the inner diameter φ_(a) of the sheathdistal portion 50 is configured so that it becomes gradually smallertoward the distal side and only the hydrophobic coating 71 having afriction coefficient lower than the friction coefficient of the sheathtube 21 is formed only on the inner surface 50 a of the sheath distalportion 50.

Also, in a case in which reduction in the penetration resistance of theouter surface 50 b in the sheath distal portion 50 is to be mainlyachieved, it is sufficient if the hydrophilic lubricating coating 73 isprovided on the outer surface 60 b of the sheath main body portion 60and the hydrophobic coating 72 having a friction coefficient lower thanthe friction coefficient of the hydrophilic lubricating coating 73during the dry period thereof is formed on the outer surface 50 b of thesheath distal portion 50. In this case, the hydrophobic coating of theinner surface 50 a in the sheath distal portion 50 is not indispensable.

The detailed description above describes features and aspects ofembodiments of an introducer sheath and introduce assembly. But theinvention here is not limited to the precise embodiments and variationsdescribed. Changes, modifications and equivalents can be employed by oneskilled in the art without departing from the spirit and scope of theinvention as defined in the appended claims. It is expressly intendedthat all such changes, modifications and equivalents which fall withinthe scope of the claims are embraced by the claims.

1. An introducer sheath comprising: an elongated tubular memberpossessing a distal-most end and configured to be inserted in a livingbody tissue, the tubular member including a distal portion and a mainbody portion; the distal portion terminating distally at a distal-mostend of the distal portion, the distal-most end of the tubular member andthe distal-most end of the distal portion being the same, the distalportion possessing an outer surface; the main body portion having adistal-most end connected to and extending proximally from aproximal-most end of the distal portion so that the main body portion islocated entirely proximally of the distal portion, the main body portionpossessing an outer surface; the elongated tubular member including athrough hole extending throughout a longitudinal extent of the tubularmember and opening to the distal-most end of the elongated tubularmember, the through hole being configured to receive an elongated body,the through hole possessing an inner diameter; the elongated tubularmember being comprised of a taper portion in which the inner diameter ofthe through hole gradually and continuously tapers to the distal-mostend of the elongated tubular member so that the inner diameter of thethrough hole in the taper portion is smaller at the distal-most end ofthe taper portion than at a proximal-most end of the taper portion; ahydrophilic lubricating coating on an outer surface of the main bodyportion; a hydrophobic coating on the inner surface of the through holein the taper portion, the hydrophobic coating extending proximally fromthe distal-most end of the tubular member toward the main body portion;and the hydrophobic coating possessing a friction coefficient lower thanthe friction coefficient of the hydrophilic lubricating coating beforethe hydrophilic lubricating coating contacts liquid.
 2. The introducersheath according to claim 1, wherein the hydrophobic coating on theinner surface of the through hole extends continuously from thedistal-most end of the tubular member, throughout the entirety of thelongitudinal extent of the taper portion and into the main body portionof the tubular member.
 3. The introducer sheath according to claim 2,wherein the inner diameter of the through hole in the main body portiondoes not taper in a narrowing manner toward the distal portion.
 4. Theintroducer sheath according to claim 3, wherein the taper portion of thedistal portion possesses an outer diameter that gradually andcontinuously tapers to the distal-most end of the elongated tubularmember so that the outer diameter of the taper portion at thedistal-most end of the taper portion is smaller than the outer diameterof the proximal-most end of the taper portion, the hydrophobic coatingcovering the entire outer surface of the taper portion and also coveringthe outer surface of a part of the distal portion which possesses aconstant outer diameter.
 5. The introducer sheath according to claim 3,wherein the taper portion possesses an outer surface, and furthercomprising a hydrophobic coating on the outer surface of the taperportion and extending proximally from the distal-most end of the taperportion toward the main body portion.
 6. The introducer sheath accordingto claim 1, wherein the distal portion of the elongated tubular memberincludes a non-taper portion positioned entirely proximally of the taperportion, the inner diameter of the hollow portion in the non-taperportion being constant, the hydrophobic coating extending continuouslyfrom the distal-most end of the tubular member, throughout the entiretyof the longitudinal extent of the taper portion, throughout the entiretyof the longitudinal extent of the non-taper portion and into the mainbody portion of the tubular member.
 7. The introducer sheath accordingto claim 1, wherein the distal-most end of the main body portion isconnected to the proximal-most end of the distal portion at a boundaryportion, the hydrophobic coating overlying the hydrophilic lubricatingcoating at the boundary portion.
 8. An introducer sheath comprising: atubular member possessing a hollow portion through which an elongatedbody is freely insertable, the tubular member including a distal portionand a main body portion; the hollow portion of the distal portionpossessing an inner diameter which becomes gradually smaller toward adistal end of the tubular member; and the distal portion possessing aninner surface provided with a hydrophobic coating having a frictioncoefficient lower than the friction coefficient of the tubular member.9. The introducer sheath according to claim 8, wherein the hydrophobiccoating is also provided on an outer surface of the distal portion. 10.The introducer sheath according to claim 9, wherein the main bodyportion possesses an outer surface, and further comprising a hydrophiliclubricating coating on the outer surface of the main body portion, thehydrophobic coating possessing a friction coefficient lower than thefriction coefficient of the hydrophilic lubricating coating before thehydrophilic lubricating coating contacts liquid.
 11. The introducersheath according to claim 10, wherein at a boundary portion between thedistal portion and the main body portion, the hydrophobic coatingoverlies the hydrophilic lubricating coating.
 12. The introducer sheathaccording to claim 10, wherein when swelling by absorbing blood, thehydrophilic lubricating coating has an outer diameter approximatelyequal to or greater than the outer diameter of the hydrophobic coating.13. The introducer sheath according to claim 8, wherein the hydrophobiccoating on the inner surface of the distal portion extends continuouslyfrom a distal-most end of the tubular member, throughout the entirety ofthe longitudinal extent of a part of the distal portion at which theinner diameter is gradually becoming smaller, and into the main bodyportion of the tubular member.
 14. The introducer sheath according toclaim 8, wherein the inner diameter of the hollow portion in the mainbody portion does not taper in a narrowing manner toward the distalportion.
 15. An introducer assembly comprising: a dilator possessing anouter surface; an introducer sheath comprised of: a tubular memberpossessing a through hole, the tubular member including a distal portionand a main body portion; the distal portion of the tubular memberincluding a taper portion at which an inner diameter of the through holebecomes gradually smaller toward a distal end of the taper portion; andthe inner surface of the taper portion being provided with a hydrophobiccoating having a friction coefficient lower than the frictioncoefficient of the tubular member; and the dilator being positionedinside the through hole in the tubular member, the dilator possessing adistal-most end extending distally beyond a distal-most end of the taperportion.
 16. The introducer assembly according to claim 15, wherein atleast a portion of the inner surface of the through hole in the distalportion and a portion of the outer surface of the dilator are attachedthrough the hydrophobic coating.
 17. The introducer assembly accordingto claim 16, wherein the hydrophobic coating is comprised of areactive-curing coating material, and is formed by reactively curing thereactive-curing coating material while the dilator is positioned insidethe through hole in the tubular member.
 18. The introducer assemblyaccording to claim 16, wherein the at least a portion of the innersurface of the through hole in the distal portion and the portion of theouter surface of the dilator are attached through the hydrophobiccoating by an attaching force smaller than the force acting on theattachment region when the dilator is pulled out from the introducersheath.
 19. The introducer assembly according to claim 15, wherein theintroducer sheath and the dilator are attached to each other byreactively curing the hydrophobic coating during gas sterilization. 20.The introducer assembly according to claim 15, wherein the main bodyportion possesses an outer surface, and further comprising a hydrophiliclubricating coating on the outer surface of the main body portion, thehydrophobic coating possessing a friction coefficient lower than thefriction coefficient of the hydrophilic lubricating coating before thehydrophilic lubricating coating contacts liquid.